Talk:Sunbeam Arab

Recent text dump
I am parking the recently added but unreferenced text dump and editor's comments here as they might be useful. Nimbus (talk) 11:47, 29 September 2008 (UTC)

THE 'ARAB 1' SUNBEAM - COATALEN WATER COOLED AIRCRAFT ENGINE 90 DEGREE V-8. Nose Piece Cast Integral with Crankcase. Reduction 1.557 to 1. Three valves per Cyl. 120 m/m Bore. 130 m/m Stroke Master Rod Side, 141 m/m stroke Link Rod Side. Piston Displacement Master Rod side is 5.881 Liters. Piston Displacement Link Rod side is 6.379 Liters. Total Piston Displacement is 12.259 Liters. Articulating Connecting Rod System. 208 H.P. Test Brake Horsepower. Normal R.P.M. 2,000. Approximate weight per H.P. is 2.5 to 1. Weight Dry: 550 lbs. engine complete, including propeller boss, but without oil and water Maximum Permissible Speed for periods not exceeding five minutes: 2,100 r.p.m. Maximum Horsepower at 2,000 R.P.M. 235. Average fuel consumption is .54 pints per h.p. hour. (228 H.P. obtained on .49 Pints Per Hour.) Claudel Hobson Carburetor: Type H.C.7 set in Center of V formed by Cylinder Blocks. Maximum Fuel Pressure 4 lbs/sq.in. Direction of Crankshaft Rotation is Clockwise, Pilots View. Firing Order is 1, 1A, 2, 2A, 4, 4A 3, 3A. CYL. #1 IS LEFT REAR 1A IS RIGHT FRONT. ALL "A" CYLINDERS ARE ON THE RIGHT, PILOTS VIEW. Dual Magneto Ignition plus Two Sparkplugs per Cylinder. Lubricant is Pharmaceutical Castor Oil, 3 Pints Per Hour, Normal Oil Pressure to Main Engine Details is 45 P. /S./I. @ full Power. Pressure to camshaft is not to exceed 20 P./S./IN. Nor fall below 3/P./S./I. From Air Board Technical Department: Issue No. T276 May 1918

This engine was infamous for its excessive vibration, which was far worse than the Hispano-Suiza of the same bore but without the Articulated Con Rods, which produced a different stroke on the one bank of cylinders. There is no notation anywhere that I have seen that states whether this engine had a balanced crankshaft or not. Altho the 180 degree crankshaft of the Hispano-Suiza had imbalance of both the Primary and Secondary. This engine was worse due to the Articulated Rods as they do not follow a circular path that should follow the same path as the Master rod side of the block. A drawing of the noncircular path of the Link rod will reveal this unwanted condition.

Willys-Overland
According to Profile 21 The Bristol Fighter, Sunbeam Arab engines were ordered from Austin Motor Co, and from Willys-Overland of Canada Ltd, Toronto. Toronto production was delayed by the "extraordinary" decision to covert the drawings from metric to inches. The Wikipedia page as of 2021/05/02 quotes the bore and stroke as 4.72"&times;5.12". Are there any other references out there on the Sunbeam Arab? The decision to design this thing in metric is remarkable, but the bore and stroke work out very closely to 120mm&times;130mm. Is there a reference that explicitly assigns this manufacturing to Willys-Overland USA?


 * I don't have the source used for the specs section but other sources give the dimensions in metric round numbers (along with other Sunbeam engines). It was very common for early British engines to use metric dimensions, the de Havilland Gipsy Major is a good example, originally derived from Renault tractor cylinders. Louis Coatalen was French. Many French engine types were license produced in the UK.


 * There is a Wikipedia convention of using the producing nation's units first (Manual of Style/Dates and numbers), so the Supermarine Spitfire is Imperial and the Messerschmitt Bf 109 is metric.Nimbus (Cumulus nimbus floats by)  10:46, 3 May 2021 (UTC)